https://dev.mysql.com/mysql-eof.html
In this case, a NULL return from mysql_fetch_row() always means the end of the result set has been reached and it is unnecessary to call mysql_eof(). Because an error may occur on the connection during this process, a NULL return value from ...
https://dev.mysql.com/mysql-error.html
const char *mysql_error(MYSQL *mysql) For the connection specified by mysql, mysql_error() returns a null-terminated string containing the error message for the most recently invoked API function that failed. If a function did not fail, the return ...
https://dev.mysql.com/mysql-fetch-field-direct.html
For metadata-optional connections, this function returns NULL when the resultset_metadata system variable is set to NONE. MYSQL_FIELD *mysql_fetch_field_direct(MYSQL_RES *result, unsigned int fieldnr) Given a field number fieldnr for a column ...
https://dev.mysql.com/mysql-fetch-fields.html
For metadata-optional connections, this function returns NULL when the resultset_metadata system variable is set to NONE. MYSQL_FIELD *mysql_fetch_fields(MYSQL_RES *result) Returns an array of all MYSQL_FIELD structures for a result set. Each ...
https://dev.mysql.com/mysql-field-count.html
The normal use of this function is when mysql_store_result() returned NULL (and thus you have no result set pointer). See Section 28.7.28.1, “Why mysql_store_result() Sometimes Returns NULL After mysql_query() Returns Success”. unsigned int ...
https://dev.mysql.com/mysql-list-dbs.html
wild may contain the wildcard characters % or _, or may be a NULL pointer to match all databases. MYSQL_RES *mysql_list_dbs(MYSQL *mysql, const char *wild) Returns a result set consisting of database names on the server that match the simple ...
https://dev.mysql.com/mysql-list-fields.html
wild may contain the wildcard characters % or _, or may be a NULL pointer to match all fields. MYSQL_RES *mysql_list_fields(MYSQL *mysql, const char *table, const char *wild) Note mysql_list_fields() is deprecated and will be removed in a future ...
https://dev.mysql.com/mysql-list-tables.html
wild may contain the wildcard characters % or _, or may be a NULL pointer to match all tables. MYSQL_RES *mysql_list_tables(MYSQL *mysql, const char *wild) Returns a result set consisting of table names in the current database that match the simple ...
https://dev.mysql.com/mysql-num-fields.html
You would use the connection handler if mysql_store_result() or mysql_use_result() returned NULL (and thus you have no result set pointer). See Section 28.7.28.1, “Why mysql_store_result() Sometimes Returns NULL After mysql_query() Returns ...
https://dev.mysql.com/mysql-options4.html
This example demonstrates the calls that specify connection attributes: MYSQL mysql; mysql_init(&mysql); mysql_options(&mysql,MYSQL_OPT_CONNECT_ATTR_RESET, 0); mysql_options4(&mysql,MYSQL_OPT_CONNECT_ATTR_ADD, "key1", "value1"); ... int ...
